103 lines
2.2 KiB
C#
103 lines
2.2 KiB
C#
using BizHawk.Common;
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using BizHawk.Common.NumberExtensions;
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namespace BizHawk.Emulation.Cores.Nintendo.NES
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{
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// http://wiki.nesdev.com/w/index.php/INES_Mapper_225
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internal sealed class Mapper225 : NesBoardBase
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{
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bool prg_mode = false;
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int chr_reg;
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int prg_reg;
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byte[] eRAM = new byte[4];
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int chr_bank_mask_8k, prg_bank_mask_16k, prg_bank_mask_32k;
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public override bool Configure(EDetectionOrigin origin)
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{
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switch (Cart.BoardType)
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{
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case "MAPPER225":
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case "MAPPER255": // Duplicate of 225 accoring to: http://problemkaputt.de/everynes.htm
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break;
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default:
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return false;
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}
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chr_bank_mask_8k = Cart.ChrSize / 8 - 1;
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prg_bank_mask_16k = Cart.PrgSize / 16 - 1;
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prg_bank_mask_32k = Cart.PrgSize / 32 - 1;
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SetMirrorType(EMirrorType.Vertical);
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return true;
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}
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public override void SyncState(Serializer ser)
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{
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ser.Sync(nameof(prg_reg), ref prg_reg);
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ser.Sync(nameof(chr_reg), ref chr_reg);
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ser.Sync(nameof(prg_mode), ref prg_mode);
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ser.Sync(nameof(eRAM), ref eRAM, false);
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base.SyncState(ser);
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}
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public override void WritePrg(int addr, byte value)
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{
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addr += 0x8000;
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prg_mode = addr.Bit(12);
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if (addr.Bit(13))
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{
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SetMirrorType(EMirrorType.Horizontal);
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}
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else
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{
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SetMirrorType(EMirrorType.Vertical);
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}
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int high = (addr & 0x4000) >> 8;
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prg_reg = (addr >> 6) & 0x3F | high;
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chr_reg = addr & 0x3F | high;
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}
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public override byte ReadPrg(int addr)
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{
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if (prg_mode == false)
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{
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int bank = (prg_reg >> 1) & prg_bank_mask_32k;
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return Rom[(bank * 0x8000) + addr];
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}
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else
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{
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return Rom[((prg_reg & prg_bank_mask_16k) * 0x4000) + (addr & 0x3FFF)];
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}
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}
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public override byte ReadPpu(int addr)
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{
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if (addr < 0x2000)
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{
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return Vrom[((chr_reg & chr_bank_mask_8k) * 0x2000) + addr];
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}
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return base.ReadPpu(addr);
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}
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public override void WriteExp(int addr, byte value)
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{
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if (addr >= 0x1800)
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{
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eRAM[(addr & 0x03)] = (byte)(value & 0x0F);
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}
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}
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public override byte ReadExp(int addr)
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{
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if (addr >= 0x1800)
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{
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return eRAM[addr & 0x03];
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}
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return base.ReadExp(addr);
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}
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}
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}
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